As is known from WO 2012/148576 A1, for example, in a device used in the packaging industry for decorating hollow bodies, each of which has a cylindrical lateral surface, in most cases a plurality of printing units are used. In such cases, each of these printing units transfers a printing ink onto a printing blanket, which is used jointly by these printing units. The lateral surface of the hollow body in question is then decorated with a print motif, e.g. a multicolored print motif, by a relative movement between the lateral surface of the hollow body in question and the printing blanket, in particular by rolling the lateral surface of the hollow body in question along said printing blanket, which has been inked-up in advance, in particular with multiple colors.
A device of this type for printing on or for decorating hollow bodies, each of which has in particular a preferably cylindrical lateral surface, is used, for example, in conjunction with a system for producing such hollow bodies which typically has a plurality of work stations, wherein the hollow bodies are printed on or decorated by means of a printing process, and therefore these hollow bodies may also be referred to generally as printed products. In such a system, the hollow bodies to be printed on are produced in a large-scale production process in which, for example, several hundred or even several thousand pieces are produced per minute, for example between 1500 and 3000 pieces per minute. Hollow bodies of this type are made of metal, in particular steel or aluminum, for example, or are made of plastic. Metal hollow bodies of this type are used, for example, as beverage cans or as aerosol cans. Plastic hollow bodies of this type are produced, e.g. in the form of thermoplastic molded articles and are used, e.g. as cartons for packaging liquid or paste-like food products, for example, especially dairy products or beverages. However, the hollow body may also be a round tubular body made of either a plastic or aluminum, with a tube being defined as an elongated, sturdy but malleable container, which is intended for filling particularly with a paste-like substance. Tubes made of aluminum are produced, e.g. in a backward extrusion process. Tubes made of plastic are produced as seamless tubes, e.g. by means of extrusion. Another possible type of hollow body that can be printed on in a device as described above is containers or vessels, such as bottles or flasks, preferably cylindrical and made of glass.
Beverage cans are preferably made of aluminum and are typically what are known as two-part cans, in which a circular base together with a preferably straight cylinder shell are produced from of a single work piece, i.e. from a slug or from a blank, i.e. a circular disk, in a forming process, for example in a cold extrusion process or in a tensile-pressure forming process, preferably by deep drawing, in particular by deep drawing and ironing, to form a hollow body which is open at one end, known as a can blank, and in which, in a final manufacturing step, a circular lid is placed on the cylinder and is attached to the cylinder by flanging, forming an air-tight seal.
Tinplate cans are another type of can. Tinplate is tin-plated sheet steel. The thickness of the sheet steel used to produce tinplate cans is 0.15 mm to 0.49 mm, for example, and the thickness of the tin plating is 0.2 μm to 0.8 μm, for example; the tin plating provides protection against corrosion. Tinplate cans are what are known as three-part cans. To produce the shell for a tinplate can, a rectangular strip of sheet steel is bent into a preferably straight cylinder, and the ends of this strip that has been bent into a cylinder are welded together at a butt joint. A circular base and a circular lid are then placed onto the cylinder and the edges are flanged. To make the tinplate can in question more resistant to dents, each of the three parts, i.e., the cylinder shell, the base, and the lid, preferably has a corrugated profile, for example.
An aerosol can, also called a spray can, is a metal can used for spraying liquids. The liquid filled into an aerosol can is pressurized, and propane, butane, dimethyl ether, or mixtures thereof, or compressed air or nitrogen, for example, is used as the propellant for dispensing the liquid from the can.
The aforementioned WO 2012/148576 A1 describes a device for decorating cans, in which an assembly of multiple printing units is provided, each having an inking unit for the multicolored decoration of a plurality of cans, wherein each of the inking units belonging to one of the printing units has an ink fountain for supplying ink, wherein in each ink fountain, an ink fountain roller for picking the printing ink up from the associated ink fountain is provided, wherein in each inking unit, a duct roller is provided, each duct roller receiving printing ink from the ink fountain roller in question, wherein in a roller train situated downstream of the respective duct roller in the inking unit in question, a plurality of oscillating ink distribution rollers and a plurality of ink transfer rollers are provided, each interacting with at least one of the ink distribution rollers, wherein for each inking unit, a plate cylinder having at least one printing plate is provided, and only a single ink forme roller cooperates with each plate cylinder to apply the printing ink.
The subsequently published DE 10 2016 201140 A1 discloses a method for printing on hollow bodies in which printing ink is transferred to each of the hollow bodies by one of the printing blankets arranged one behind the other on the periphery of a segmented wheel rotating about its axis, in which at least two plate cylinders, arranged in succession in the direction of rotation of the segmented wheel and each bearing a printing plate, are used.
WO 2004/109581 A2 discloses an apparatus for carrying out a contactless digital printing method, e.g. an inkjet printing method, for printing on round objects, in particular two-part cans, individually if necessary, without the use of a printing blanket, in which a plurality of print heads are preferably provided, each of which prints in a single printing ink.
From DE 10 2006 004568 A1, a short inking unit for a printing machine is known, comprising a printing forme cylinder, an ink forme roller cooperating with the printing forme cylinder, and an anilox roller that contacts the ink forme roller and is associated with a device for supplying ink, wherein at least one leveling roller is disposed between the point where ink is supplied and the contact nip between the anilox roller and the ink forme roller with respect to the direction of rotation of the anilox roller, and the device for supplying ink is embodied as a chamber doctor blade.
Known from DE 101 60734 A1 is a printing machine that comprises at least one printing forme, a dampening unit for dampening the printing forme with a dampening medium, an inking unit for inking the printing forme with a printing ink and a dehumidifying device with a heating roller (temperature control roller) for reducing the amount of dampening medium that is conveyed together with the printing ink, wherein the inking unit is embodied as a leverless short inking unit, in which one inking unit roller of the inking unit includes a first rolling contact point at which the inking unit roller is in rolling contact with the heating roller, and the inking unit roller also has a second rolling contact point, and wherein the shortest path along which printing ink is conveyed from the inking unit roller to the printing forme is determined by at most one intermediate roller.
Known from DE 32 32780 A1 is an inking unit for offset printing machines for printing onto sheets or webs, having a plate cylinder that receives the necessary ink from at most two ink forme rollers which have an elastic surface and which cooperate with an inking cylinder to which the ink is fed via an ink feeding system that generates a continuous ink film, wherein an ink forme roller having nearly the same diameter as the plate cylinder is disposed downstream of the inking cylinder, wherein the inking cylinder is associated with a dampening unit having at least one roller for transferring the dampening medium, and wherein the dampening medium is transferred to the inking cylinder in the direction of rotation thereof downstream of the ink application and upstream of the contact point thereof with the ink forme roller.
Known from DE 10 2006 048286 A1 is a method for driving a printing unit which has a short inking unit in a processing machine having an anilox roller and an associated doctor blade device, along with an ink forme roller located downstream of the anilox roller, and a plate/forme cylinder downstream of the ink forme roller in the direction of ink flow, wherein the plate/forme cylinder is operatively connected to a rubber blanket cylinder and the rubber blanket cylinder is operatively connected to a printing cylinder which guides the printing substrate, wherein the anilox roller is driven by an independent drive, wherein during printing/varnishing operation, the main drive supplies an input drive to a drive wheel of the printing cylinder and to a drive wheel of the rubber blanket cylinder and to a second and a first drive wheel of the plate/forme cylinder and to a drive wheel of the ink forme roller and to a drive wheel of the anilox roller, while the independent drive of the anilox roller is inactive, and wherein during set-up operation, the drive connection to the main drive between first drive wheel and second drive wheel of the plate/forme cylinder is disconnected, the independent drive of the anilox roller is activated, and the independent drive applies drive torque to the drive wheel of the anilox roller and to the drive wheel of the ink forme roller and to the first drive wheel of the plate/forme cylinder.
Known from DE 196 24440 A1 is a device for filling depressions in a cylinder of a printing machine with a fluid, wherein at least two doctor blade devices for filling depressions in the cylinder with the fluid are arranged on the cylinder, wherein an applicator for the fluid, connected to a fluid conveyance system, and a working blade disposed downstream of said applicator in the direction of rotation of the cylinder are provided, wherein the doctor blades are mounted on a bar, and the wiped off fluid is discharged to a collecting basin.
Known from DE 89 12194 U1 is an inking unit for use in a printing machine, having a working doctor blade that can be set against an anilox roller, along with an ink trough with ink conveying means, wherein the working doctor blade, the ink trough, and the means for conveying the ink to the anilox roller are combined to form a single modular unit and the modular unit is removably attachable to a carrier structure mounted on the printing machine.
Known from DE 10 2007 052761 A1 is an anilox printing unit, which includes an ink forme roller and an anilox roller as inking unit rollers, the anilox roller being mounted on rocking levers, wherein the anilox roller and the ink forme roller each have bearer rings, and a device for pressing the bearer rings of one inking unit roller against the bearer rings of the other inking unit roller includes springs to compensate for diameter differences resulting from manufacturing tolerances.
DE 43 00683 A1 discloses an inking unit of a rotary printing press, having an ink forme roller with annular grooves formed in its lateral surface.
A distribution roller having a plurality of pliable rings arranged side by side in the axial direction is known from U.S. Pat. No. 516,620.
Known from DE 28 51426 A1 is a device for printing on the lateral surface of hollow bodies, wherein a transport device is provided for transporting the hollow bodies to be printed about a rotational axis, wherein a plurality of printing units are provided, wherein each hollow body to be printed on can be transported by means of the transport device into the printing zone of at least one of the printing units, and wherein at least one of the printing units has a printing forme cylinder and an inking unit having a single ink forme roller.